投資計算機

Project your investment growth, analyze ROI, and see how inflation and taxes affect your returns. Get instant results with growth charts and year-by-year breakdown.

あなたの詳細

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S&P 500 過去の平均: ~10%

調整 (オプション)

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Enter your initial investment, monthly contribution, expected return, and period. Optionally add inflation and tax rate, then click Calculate to see projected growth, ROI, and scenarios.

完全なユーザーガイド

What is ROI and CAGR?

ROI (Return on Investment) measures total return as a percentage of what you put in. CAGR (Compound Annual Growth Rate) is the smoothed annual return that accounts for compounding over time. This calculator projects growth with monthly contributions, then applies inflation and tax adjustments so you see both nominal and real outcomes.

What Your Results Mean

最終残高

Projected value at the end of the period before taxes; includes contributions and investment gains.

インフレ調整後の値

Today's purchasing power of your future balance. Inflation reduces real value over time.

税引後価格

Estimated value after capital gains tax on investment gains. Use your expected tax rate.

この計算機の使い方

  1. Enter initial investment and/or monthly contribution
  2. Set expected annual return and investment period in years
  3. Optionally add inflation rate and capital gains tax rate
  4. Click Calculate to see summary, growth chart, breakdown, and scenarios

重要な注意事項

  • This calculator is for education and estimation only. Not financial or investment advice.
  • Actual returns vary. Past performance does not guarantee future results.
  • Consider consulting a financial advisor for your situation.

投資のヒント

  • Diversify across asset classes; don't put all eggs in one basket.
  • Use tax-advantaged accounts (401k, IRA) when possible.
  • Keep fees low; they compound against you over time.
  • Stay invested long-term; time in the market beats timing the market.

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